During the years 1974 and 1975 at our institution, 587 patients who had suffered previous myocardial infarctions underwent anesthesia and surgery. Thirty-six (6.1%) had a reinfarction and 25 (69%) died. Patients operated on within three months of the previous infarction had a 27% reinfarction rate. This decreased to 11% if the infarct had occurred three to six months previously and stabilized at 4% to 5% if the interval was more than six months. Risk factors associated with significantly increased reinfarction rates included preoperative hypertension, intraoperative hypotensive episodes, and noncardiac thoracic or upper abdominal operations of more than three hours' duration. Time under anesthesia was strikingly correlated with reinfarction rates in the entire group. Postoperative intensive care unit admission did not significantly affect the reinfarction rate, nor did diabetes, angina, patient age or sex, or site of the previous myocardial infarction.